The structure of elements of adenovirus 2 DNA which regulate the synthesis and maturation of adenovirus messenger RNA will be investigated. Cytoplasmic adenovirus messenger will be isolated late in infection from productively infected cells. Radioactive DNA copies of messenger 3' termini will be prepared by oligo dT primed reverse transcription. The sites in the adenovirus genome coding for mRNA termini will be identified through hybridization of these transcripts to adenovirus DNA restriction fragments. The nucleotide sequences generating messenger termini will be determined by applying newly developed DNA sequencing methodology to both the reverse transcripts and the adenovirus DNA template coding for messenger end groups. The initiation, termination, and processing steps by which cytoplasmic messenger RNA is produced from primary adenovirus transcripts will be investigated by applying RNA sequencing methodology to P32 labelled products prepared from isolated adeno infected nuclei. Taken together, these investigations will provide a molecular description of the mechanisms of gene expression by an eukaryotic viral genome.